This invention relates to the field of separating apparatus, and particularly to apparatus for separating weakly magnetic particles from the non-magnetic particles of a mixture of the two. Here, the word "magnetic" refers to particles which are magnetically susceptible, and is not meant to imply particles which are themselves permanently magnetized. The procedure is very important in modern iron mining operations, where the ore is of relatively low grade and contains much gangue. An example is the operation of taconite mining where the ores are of relatively low grade, contain primarily weakly magnetic iron minerals, and are commonly referred to as "oxidized taconite". Such ores are generally no better than the discarded "tailings" of earlier iron mining operations, and indeed those tailings may become a valuable source of iron by the use of the separator of the present invention.
Applicant is aware of the following U.S. Pat. Nos. 3,947,349 and 4,046,680 to Fritz which both show permanent magnet high intensity separators; and 4,874,508 to Fritz which shows a magnetic separator.